Since laminated glass generates only a small amount of scattering glass fragments even when subjected to external impact and broken, laminated glass is excellent in safety. As such, the laminated glass is widely used for automobiles, railway vehicles, aircraft, ships, buildings and the like. The laminated glass is produced by sandwiching an interlayer film for laminated glass between a pair of two glass plates.
As the laminated glass used for automobiles, a head-up display (HUD) has been known. In the HUD, on the windshield of an automobile, measured information such as the speed which is traveling data of the automobile and the like can be displayed.
In the HUD, there is a problem that the measured information displayed on the windshield is doubly observed.
In order to suppress double images, the following Patent Document 1 discloses a sheet of laminated glass in which a wedge-shaped interlayer film having a prescribed wedge angle is sandwiched between a pair of glass plates. In such a sheet of laminated glass, by the adjustment of the wedge angle of the interlayer film, a display of measured information reflected by one glass plate and a display of measured information reflected by the other glass plate can be focused into one point to make an image in the visual field of a driver. As such, the display of measured information is hardly observed doubly and the visibility of a driver is not hindered.
Moreover, laminated glass used for the opening part of vehicles and buildings is required to have high heat shielding properties.
The energy amount of an infrared ray with a wavelength of 780 nm or more which is longer than that of visible light is small as compared with that of an ultraviolet ray. However, the thermal action of infrared rays is large, and when infrared rays are absorbed into a substance, heat is released from the substance. As such, infrared rays are generally called heat rays. Accordingly, in order to heighten the heat shielding properties of laminated glass, it is necessary to sufficiently cut off infrared rays.
As an interlayer film including heat shielding particles for effectively cutting off the infrared rays (heat rays), the following Patent Document 2 discloses an interlayer film including tin-doped indium oxide particles (ITO particles) or antimony-doped tin oxide particles (ATO particles). The following Patent Document 3 discloses an interlayer film including tungsten oxide particles.